Custom scheme registration fails

[LeadAssimilator]

Description
Custom registered schemes never get registered in the subprocesses causing them to not work.

To Reproduce

1. Register a custom scheme.
2. Try to nav to a url with the custom scheme.
3. Observe custom scheme load failed and VALIDATION_ERROR_DESERIALIZATION_FAILED errors in log.

Expected behavior
Custom schemes should work.

Versions:

• OS: Ubuntu 22.0.4.1 LTS [via wsl2]
• Java Version: Microsoft OpenJDK 17.0.3+7-LTS
• JCEF Version: 87476e9
• CEF Version: 110.0.25

Additional context
JCEF is erroneously constructing temp file names used for the scheme registration that the subprocess helper needs. There is a bad assumption that CefGetPath will return a temp path with a trailing slash in util::GetTempFileName.

Workarounds

• export TMPDIR=/tmp/
• sudo chmod o+w / (dont do this)

Proposed Fix
Check for and insert a trailing slash as needed or use std::filesystem::path to avoid these kinds of errors.